Recent progress in biodiversity research on the Xylariales and their secondary metabolism

Molecular networking and computational NMR analyses uncover six polyketide-terpene hybrids from termite-associated Xylaria isolates

Fungi constitute the Earth's second most diverse kingdom, however only a small percentage of these have been thoroughly examined and categorized for their secondary metabolites, which still limits our understanding of the ecological chemical and pharmacological potential of fungi. In this study, we explored members of the co-evolved termite-associated fungal genus Xylaria and identified a family of highly oxygenated polyketide-terpene hybrid natural products using an MS/MS molecular networking-based dereplication approach. Overall, we isolated six no yet reported xylasporin derivatives, of which xylasporin A (1) features a rare cyclic-carbonate moiety. Extensive comparative spectrometric (HRMS2) and spectroscopic (1D and 2D NMR) studies allowed to determine the relative configuration across the xylasporin family, which was supported by chemical shift calculations of more than 50 stereoisomers and DP4+ probability analyses. The absolute configuration of xylasporin A (1) was also proposed based on TDDFT-ECD calculations. Additionally, we were able to revise the relative and absolute configurations of co-secreted xylacremolide B produced by single x-ray crystallography. Comparative genomic and transcriptomic analysis allowed us to deduce the putative biosynthetic assembly line of xylasporins in the producer strain X802, and could guide future engineering efforts of the biosynthetic pathway.

Abundance and diversity of fungal endophytes isolated from monk fruit (Siraitia grosvenorii) grown in a Canadian research greenhouse

Monk fruit (Siraitia grosvenorii) is an herbaceous perennial vine of the Cucurbitaceae family cultivated commercially mainly in southern China. There is very little information available about the fungal endophytes in monk fruit. In this study, monk fruit plants were grown from seeds in a research greenhouse at Kwantlen Polytechnic University in British Columbia, Canada to explore the abundance and diversity of their fungal endophytes. Fungal endophytes were isolated from seeds, seedlings, mature monk fruit plants, and fruits, and cultured on potato dextrose agar and water agar media. Isolates were identified by microscopic examination and BLAST comparison of ITS sequences to published sequences in GenBank. At least 150 species of fungal endophytes representing 60 genera and 20 orders were recovered from monk fruit tissues. Non-metric multidimensional scaling (NMDS) was carried out to explore the similarity of fungal communities among roots, stems, leaves, flowers, fruits, and seeds based on fungal orders. Our study showed that monk fruit plants are a rich source of fungal endophytes with the greatest abundance and diversity in leaves. This work has deepened our understanding of the intricate interactions between plants and fungi that sustain ecosystems and underpin plant health and resilience.

Diversity of Leaf Fungal Endophytes from Two Coffea arabica Varieties and Antagonism towards Coffee Leaf Rust

Coffee has immense value as a worldwide-appreciated commodity. However, its production faces the effects of climate change and the spread of severe diseases such as coffee leaf rust (CLR). The exploration of fungal endophytes associated with Coffea sp. has already found the existence of nearly 600 fungal species, but their role in the plants remains practically unknown. We have researched the diversity of leaf fungal endophytes in two Coffea arabica varieties: one susceptible and one resistant to CLR. Then, we conducted cross-infection essays with four common endophyte species (three Colletotrichum sp. and Xylaria sp. 1) and Hemileia vastatrix (CLR) in leaf discs, to investigate the interaction of the endophytes on CLR colonisation success and severity of infection. Two Colletotrichum sp., when inoculated 72 h before H. vastatrix, prevented the colonisation of the leaf disc by the latter. Moreover, the presence of endophytes prior to the arrival of H. vastatrix ameliorated the severity of CLR. Our work highlights both the importance of characterising the hidden biodiversity of endophytes and investigating their potential roles in the plant-endophyte interaction.

Fungal Endophytes: Discovering What Lies within Some of Canada's Oldest and Most Resilient Grapevines

Plant diseases and pests reduce crop yields, accounting for global crop losses of 30% to 50%. In conventional agricultural production systems, these losses are typically controlled by applying chemical pesticides. However, public pressure is mounting to curtail agrochemical use. In this context, employing beneficial endophytic microorganisms is an increasingly attractive alternative to the use of conventional chemical pesticides in agriculture. A multitude of fungal endophytes are naturally present in plants, producing enzymes, small peptides, and secondary metabolites due to their bioactivity, which can protect hosts from pathogens, pests, and abiotic stresses. The use of beneficial endophytic microorganisms in agriculture is an increasingly attractive alternative to conventional pesticides. The aim of this study was to characterize fungal endophytes isolated from apparently healthy, feral wine grapes in eastern Canada that have grown without agrochemical inputs for decades. Host plants ranged from unknown seedlings to long-lost cultivars not widely propagated since the 1800s. HPLC-MS was used to identify unique endophyte-derived chemical compounds in the host plants, while dual-culture competition assays showed a range in endophytes' ability to suppress the mycelial growth of Botrytis, which is typically controlled in viticulture with pesticides. Twelve of the most promising fungal endophytes isolated were identified using multilocus sequencing and morphology, while DNA barcoding was employed to identify some of their host vines. These fungal endophyte isolates, which consisted of both known and putative novel strains, belonged to seven genera in six families and five orders of Ascomycota. Exploring the fungal endophytes in these specimens may yield clues to the vines' survival and lead to the discovery of novel biocontrol agents.

Antiproliferative polyketides from fungus Xylaria cf. Longipes SWUF08-81 in different culture media

Bioactive compounds from the wood-decay fungus Xylaria cf. longipes SWUF08-81, cultivated in three different culture media (GM, YM and PDB), were isolated. Their structures and stereochemistry were deduced from spectroscopic and MS data analysis, together with quantum chemical calculations of 13C NMR chemical shifts and electronic circular dichroism (ECD) spectra. Five undescribed polyketides including dibenzofuran (1), mellein (2), dihydroisocoumarin (15), and two pyrans (16, 17), together with twenty-three compounds were determined. Compounds 18 and 20 were significantly toxic against cancer cell lines (HCT116, HT29, MCF-7 and HeLa) based on the MTT assay. Quantification by HPLC showed that 18 was produced three-fold higher in the broth of PDB than YM. These studies showed that the production of different compounds were primarily dependent on nutrition sources and it has given a starting point for the growth optimization conditions for the scaling up of bioactive compounds production.

Genome sequencing and molecular networking analysis of the wild fungus Anthostomella pinea reveal its ability to produce a diverse range of secondary metabolites

BACKGROUND

Filamentous fungi are prolific producers of bioactive molecules and enzymes with important applications in industry. Yet, the vast majority of fungal species remain undiscovered or uncharacterized. Here we focus our attention to a wild fungal isolate that we identified as Anthostomella pinea. The fungus belongs to a complex polyphyletic genus in the family of Xylariaceae, which is known to comprise endophytic and pathogenic fungi that produce a plethora of interesting secondary metabolites. Despite that, Anthostomella is largely understudied and only two species have been fully sequenced and characterized at a genomic level.

RESULTS

In this work, we used long-read sequencing to obtain the complete 53.7 Mb genome sequence including the full mitochondrial DNA. We performed extensive structural and functional annotation of coding sequences, including genes encoding enzymes with potential applications in biotechnology. Among others, we found that the genome of A. pinea encodes 91 biosynthetic gene clusters, more than 600 CAZymes, and 164 P450s. Furthermore, untargeted metabolomics and molecular networking analysis of the cultivation extracts revealed a rich secondary metabolism, and in particular an abundance of sesquiterpenoids and sesquiterpene lactones. We also identified the polyketide antibiotic xanthoepocin, to which we attribute the anti-Gram-positive effect of the extracts that we observed in antibacterial plate assays.

CONCLUSIONS

Taken together, our results provide a first glimpse into the potential of Anthstomella pinea to provide new bioactive molecules and biocatalysts and will facilitate future research into these valuable metabolites.

Metabolomics insights into the polyketide-lactones produced by Diaporthe caliensis sp. nov., an endophyte of the medicinal plant Otoba gracilipes

IMPORTANCE

The integration of metabolomics-based approaches into the discovery pipeline has enabled improved mining and prioritization of prolific secondary metabolite producers such as endophytic fungi. However, relying on automated untargeted analysis tools might lead to misestimation of the chemical complexity harbored in these organisms. Our study emphasizes the importance of isolation and structure elucidation of the respective metabolites in addition to deep metabolome analysis for the correct interpretation of untargeted metabolomics approaches such as molecular networking. Additionally, it encourages the further exploration of endophytic fungi from traditional medicinal plants for the discovery of natural products.

Harnessing fungal endophytes for natural management: a biocontrol perspective

In the ever-evolving realm of agriculture, the convoluted interaction between plants and microorganisms have assumed paramount significance. Fungal endophytes, once perceived as mere bystanders within plant tissues, have now emerged as dynamic defenders of plant health. This comprehensive review delves into the captivating world of fungal endophytes and their multifaceted biocontrol mechanisms. Exploring their unique ability to coexist with their plant hosts, fungal endophytes have unlocked a treasure trove of biological weaponry to fend off pathogens and enhance plant resilience. From the synthesis of bioactive secondary metabolites to intricate signaling pathways these silent allies are masters of biological warfare. The world of fungal endophytes is quite fascinating as they engage in a delicate dance with the plant immune system, orchestrating a symphony of defense that challenges traditional notions of plant-pathogen interactions. The journey through the various mechanisms employed by these enigmatic endophytes to combat diseases, will lead to revelational understanding of sustainable agriculture. The review delves into cutting-edge research and promising prospects, shedding light on how fungal endophytes hold the key to biocontrol and the reduction of chemical inputs in agriculture. Their ecological significance, potential for bioprospecting and avenues for future research are also explored. This exploration of the biocontrol mechanisms of fungal endophytes promise not only to enrich our comprehension of plant-microbe relationships but also, to shape the future of sustainable and ecofriendly agricultural practices. In this intricate web of life, fungal endophytes are indeed the unsung heroes, silently guarding our crops and illuminating a path towards a greener, healthier tomorrow.

Antibacterial and anti-Toxoplasma activities of Aspergillus niger endophytic fungus isolated from Ficus retusa: in vitro and in vivo approach

Emergent records propose that Aspergillus niger endophytic fungus is a vital source for various bioactive molecules possessing many biological properties. The current study was designed to inspect the antibacterial and anti-Toxoplasma potentials of Ficus retusa-derived endophytic fungi. After isolation and identification (using 18S rRNA gene sequencing) of A. niger endophytic fungus, LC/MS was utilized for identification and authentication of the chemical profile of the A. niger endophyte extract. Then, the fungal extract was assessed for its antibacterial and antibiofilm activities against Klebsiella pneumoniae clinical isolates. Additionally, its efficacy against Toxoplasma gondii was elucidated in vivo. The fungal extract displayed antibacterial activity against K. pneumoniae isolates with minimum inhibitory concentration values of 64-512 µg/mL. It also possessed a membrane potential dissipating effect using flow cytometry. Moreover, it formed distorted cells with rough surfaces and deformed shapes using a scanning electron microscope (SEM). Regarding its antibiofilm activity, it resulted in a dysregulation of the genes encoding biofilm formation (fimH, mrkA and mrkD) using qRT-PCR in nine K. pneumoniae isolates. The in vivo anti-Toxoplasma potential was demonstrated by decreasing the mortality rate of mice and reducing the tachyzoites' count in the peritoneal fluids and liver impression smears of mice. In addition, the deformities of the parasite decreased, as revealed by SEM and the inflammation in tissues diminished. Thus, A. niger endophytic fungi could be a valuable source of antibacterial and anti-Toxoplasma compounds.

Exploring the influence of climatic variables on mycobiome composition and community diversity in lichens: insights from structural equation modeling analysis

BACKGROUND

Lichens are symbiotic organisms composed of a fungus and a photosynthetic partner, which are key ecological bioindicators due to their sensitivity to environmental changes. The endolichenic fungi (ELF) living inside lichen thalli, are an important but understudied component of playing crucial ecological roles such as nutrient cycling and protection against environmental stressors. Therefore ELF community investigation is vital for fostering sustainable ecosystems and leveraging their ecological benefits. Deciphering the intricate relationships between ELF and their lichen hosts, alongside the influence of environmental factors on these communities, presents a significant challenge in pinpointing the underlying drivers of community structure and diversity.

RESULTS

Our research demonstrated that locational factors were the main drivers of the ELF community structure, rather than host haplotype. Several climatic factors affected the diversity of the ELF community and contributed to the prevalence of different types of fungal residents within the ELF community. A decrease in isothermality was associated with a greater prevalence of pathotrophic and saprotrophic fungi within the ELF community, resulting in an overall increase in community diversity. By conducting a structural equation modeling analysis, we identified a robust link between climatic variables, fungal trophic mode abundance, and the species diversity of the ELF community.

CONCLUSION

This study's discoveries emphasize the significance of examining climate-related factors when investigating ELF's structure and function. The connection between fungi and climate is intricate and complex, and can be influenced by various other factors. Investigating the potential for ELF to adapt to changing climatic conditions, as well as the potential effects of changes in ELF communities on lichen function, would be valuable research areas. We anticipate that our research results will establish a basis for numerous future ELF research projects and have a significant impact on the field.

Sporothioethers: deactivated alkyl citrates from the fungus Hypomontagnella monticulosa

Submerged cultivation of Hypomontagnella monticulosa MUCL 54604 resulted in formation of a stereoisomeric mixture of new sulfur-containing sporothriolide derivatives named sporothioethers A and B. The presence of the 2-hydroxy-3-mercaptopropanoic acid moiety attenuates the antimicrobial activity in comparison to the precursor sporothriolide suggesting a detoxification mechanism. However, moderate effects on biofilms of Candida albicans and Staphylococcus aureus were observed for sporothriolide and sporothioethers A and B at concentrations below their MICs.

Cytochalasans and Their Impact on Actin Filament Remodeling

The eukaryotic actin cytoskeleton comprises the protein itself in its monomeric and filamentous forms, G- and F-actin, as well as multiple interaction partners (actin-binding proteins, ABPs). This gives rise to a temporally and spatially controlled, dynamic network, eliciting a plethora of motility-associated processes. To interfere with the complex inter- and intracellular interactions the actin cytoskeleton confers, small molecular inhibitors have been used, foremost of all to study the relevance of actin filaments and their turnover for various cellular processes. The most prominent inhibitors act by, e.g., sequestering monomers or by interfering with the polymerization of new filaments and the elongation of existing filaments. Among these inhibitors used as tool compounds are the cytochalasans, fungal secondary metabolites known for decades and exploited for their F-actin polymerization inhibitory capabilities. In spite of their application as tool compounds for decades, comprehensive data are lacking that explain (i) how the structural deviances of the more than 400 cytochalasans described to date influence their bioactivity mechanistically and (ii) how the intricate network of ABPs reacts (or adapts) to cytochalasan binding. This review thus aims to summarize the information available concerning the structural features of cytochalasans and their influence on the described activities on cell morphology and actin cytoskeleton organization in eukaryotic cells.

Inhibitory Effects of the Fungal Pigment Rubiginosin C on Hyphal and Biofilm Formation in Candida albicans and Candida auris

The two fungal human pathogens, Candida auris and Candida albicans, possess a variety of virulence mechanisms. Among them are the formation of biofilms to protect yeast against harsh conditions through the development of (pseudo)hyphae whilst also facilitating the invasion of host tissues. In recent years, increased rates of antifungal resistance have been associated with C. albicans and C. auris, posing a significant challenge for the effective treatment of fungal infections. In the course of our ongoing search for novel anti-infectives, six selected azaphilones were tested for their cytotoxicity and antimicrobial effects as well as for their inhibitory activity against biofilm and hyphal formation. This study revealed that rubiginosin C, derived from stromata of the ascomycete Hypoxylon rubiginosum, effectively inhibited the formation of biofilms, pseudohyphae, and hyphae in both C. auris and C. albicans without lethal effects. Crystal violet staining assays were utilized to assess the inhibition of biofilm formation, while complementary microscopic techniques, such as confocal laser scanning microscopy, scanning electron microscopy, and optical microscopy, were used to investigate the underlying mechanisms. Rubiginosin C is one of the few substances known to effectively target both biofilm formation and the yeast-to-hyphae transition of C. albicans and C. auris within a concentration range not affecting host cells, making it a promising candidate for therapeutic intervention in the future.

Molecular and morphological characterization of Xylaria karsticola (Ascomycota) isolated from the fruiting body of Macrolepiota procera (Basidiomycota) from Bulgaria

The present study is the first to report Xylaria karsticola isolated from the basidiocarp of Macrolepiota procera (Basidiomycota), from Stara Planina Mountain, Bulgaria and second report for such species found in Europe. The fungal isolate was in vitro cultivated and the morphology was observed. It was primarily determined as a xylariaceous morphotype at the intragenus level, based on the evaluation of colony growth rate, color, and stromatic structure formation and was confirmed by unique conidiophores and conidia. The molecular identification of the isolate was performed by amplification of ITS1-5.8S-ITS2 region and the strain was identified as Xylaria karsticola with 97.57% of confidence. The obtained sequence was deposited in the GenBank database under the accession number MW996752 and in the National Bank of Industrial Microorganisms and Cell Cultures of Bulgaria under accession number NBIMCC 9097. The phylogenetic analysis of the isolate was also conducted by including 26 sequences obtained from different Xylaria isolates. Considering the phylogenetic data, X. karsticola NBIMCC 9097 was grouped along with other X. karsticola isolates, although the DNA sequence of the novel X. karsticola was rather distantly related to the other X. karsticola sequence data. The results were supported by the bootstrap analysis (100%) and indicated the different origin of the examined X. karsticola NBIMCC 9097.

Exploring the Xylariaceae and its relatives

The Xylariaceae and its relatives rank as one of the best-known members of the Ascomycota. They are now well recognized for their diversity, global distribution, ecological activities and their outstanding novel metabolites with wide ranging bioactivity.

Segregation of the genus Parahypoxylon (Hypoxylaceae, Xylariales) from Hypoxylon by a polyphasic taxonomic approach

During a mycological survey of the Democratic Republic of the Congo, a fungal specimen that morphologically resembled the American species Hypoxylon papillatum was encountered. A polyphasic approach including morphological and chemotaxonomic together with a multigene phylogenetic study (ITS, LSU, tub2, and rpb2) of Hypoxylon spp. and representatives of related genera revealed that this strain represents a new species of the Hypoxylaceae. However, the multi-locus phylogenetic inference indicated that the new fungus clustered with H. papillatum in a separate clade from the other species of Hypoxylon. Studies by ultrahigh performance liquid chromatography coupled to diode array detection and ion mobility tandem mass spectrometry (UHPLC-DAD-IM-MS/MS) were carried out on the stromatal extracts. In particular, the MS/MS spectra of the major stromatal metabolites of these species indicated the production of hitherto unreported azaphilone pigments with a similar core scaffold to the cohaerin-type metabolites, which are exclusively found in the Hypoxylaceae. Based on these results, the new genus Parahypoxylon is introduced herein. Aside from P. papillatum, the genus also includes P. ruwenzoriensesp. nov., which clustered together with the type species within a basal clade of the Hypoxylaceae together with its sister genus Durotheca.

Six Unprecedented Cytochalasin Derivatives from the Potato Endophytic Fungus Xylaria curta E10 and Their Cytotoxicity

Six previously undescribed cytochalasins, Curtachalasins X1-X6 (1-6), together with six known compounds (7-12) were isolated from the endophytic fungus Xylaria curta E10 harbored in the plant Solanum tuberosum. The structures were elucidated by the interpretation of HRESIMS, UV, and NMR data. The absolute configurations of Curtachalasins X1-X6 were determined by comparison of their experimental and calculated electronic circular dichroism (ECD) spectra. In bioassays, Curtachalasin X1 (1) and X5 (5) showed cytotoxic activity against the MCF-7 cell line with IC50 values of 2.03 μM and 0.85 μM, respectively.

Unreported cytochalasins from an acid-mediated transformation of cytochalasin J isolated from Diaporthe cf. ueckeri

Chemical investigation of an endophytic fungus herein identified as Diaporthe cf. ueckeri yielded four known compounds, named cytochalasins H and J and dicerandrols A and B. Reports of acid sensitivity within the cytochalasan family inspired an attempt of acid-mediated conversion of cytochalasins H and J, resulting in the acquisition of five polycyclic cytochalasins featuring 5/6/5/8-fused tetracyclic and 5/6/6/7/5-fused pentacyclic skeletons. Two of the obtained polycyclic cytochalasins constituted unprecedented analogues, for which the trivial names cytochalasins J₄ and J₅ were proposed, whereas the others were identified as the known phomopchalasin A, phomopchalasin D and 21-acetoxycytochalasin J₃. The structures of the compounds were determined by extensive spectral analysis, namely HR-ESIMS, ESIMS and 1D/2D NMR. The stereochemistry of cytochalasins J₄ and J₅ was proposed using their ROESY data, biosynthetic and mechanistic considerations and by comparison of their ECD spectra with those of related congeners. All compounds except for cytochalasins H and J were tested for antimicrobial and cytotoxic activity. Cytochalasins J₄ and J₅ showed neither antimicrobial nor cytotoxic activity in the tested concentrations, with only weak antiproliferative activity observable against KB3.1 cells. The actin disruptive properties of all cytochalasins obtained in this study and of the previously reported cytochalasins RKS-1778 and phomopchalasin N were examined, and monitored by fluorescence microscopy using human osteo-sarcoma (U2-OS) cells. Compared to their precursor molecules (cytochalasins H and J), phomopchalasins A and D, 21-acetoxycytochalasin J₃, cytochalasins J₄ and J₅ revealed a strongly reduced activity on the F-actin network, highlighting that the macrocyclic ring is crucial for bioactivity.

Endophytic Fungus of Achyrocline satureioides: Molecular Identification, Chemical Characterization, and Cytotoxic Evaluation of its Metabolites in Human Melanoma cell line

Endophytic fungi are important sources of anticancer compounds. An endophytic fungus was isolated from the medicinal plant Achyrocline satureioides, and molecularly identified as Biscogniauxia sp. (family Xylariaceae) based on partial nucleotide sequences of the internal transcribed spacer genomic region (GenBank Accession No. ON257911). The chemical characterization and cytotoxic properties of secondary metabolites produced by Biscogniauxia sp. were evaluated in a human melanoma cell line (A375). The fungus was grown in potato-dextrose liquid medium for 25 days, and the extracted compounds were subjected to solid-phase fractionation to obtain the purified F_DCM fraction, for which the metabolites were elucidated via ultra-performance chromatography coupled to a mass spectrometer. In the present study, 17 secondary metabolites of Biscogniauxia sp., including nine polyketide derivatives, five terpenoids, and three isocoumarins, were putatively identified. This is the first study to report of the ability of Biscogniauxia sp. in the production of isocoumarin orthosporin; the terpenoids nigriterpene A and 10-xylariterpenoid; the polyketide derivatives daldinin C, 7'dechloro-5'-hydroxygriseofulvin, daldinone D, Sch-642305, curtachalasin A, cytochalasin E, epoxycytochalasins Z8, Z8 isomer, and Z17. Furthermore, this study has reported the biosynthesis of Sch-642305 by a Xylariaceae fungus for the first time. F_DCM significantly reduced the viability and proliferation of human melanoma cells at half-maximal inhibitory concentrations ​​of 10.34 and 6.89 µg/mL, respectively, and induced late apoptosis/necrosis and cell cycle arrest in G2/M phase after 72 h of treatment. Given its ability to produce unique metabolites with promising cytotoxic effects, Biscogniauxia sp. of A. satureioides may be a reservoir of compounds with important therapeutic applications.

New cytochalasans from an endophytic Xylaria species associated with Costa Rican Palicourea elata (Rubiaceae)

Four new leucine-derived cytochalasans, possessing a 5,6,5,8-ring (1) and a 5,6,11-ring core (2-4), were isolated from a cultivated endophytic fungus Xylaria sp. strain WH2D4 (Xylariaceae). This fungus was isolated from leaves of the neotropical tree species Palicourea elata (Sw.) Borhidi (Rubiaceae) collected in Costa Rica. The chemical structures were determined by employing IR, MS as well as 1D- and 2D-NMR experiments. The stereochemistry at C-15 of compound 4 was determined by quantum calculations. The isolated compounds did not affect germination and growth of Trichoderma reesei and the opportunistic human fungal pathogen T. longibrachiatum.

Leaf decomposing fungi influence Saccharomyces paradoxus growth across carbon environments

Saccharomyces paradoxus is a model organism in ecology and evolution. However, its metabolism in its native habitat remains mysterious: it is frequently found growing on leaf litter, a habitat with few carbon sources that S. paradoxus can metabolize. We hypothesized that leaf-decomposing fungi from the same habitat break down the cellulose in leaf litter extracellularly and release glucose, supporting S. paradoxus growth. We found that facilitation by leaf-decomposing fungi was possible on cellulose and inhibition was common on glucose, suggesting diverse interactions between S. paradoxus and other fungi that have the potential to support S. paradoxus in nature.

Natural Products Lysobactin and Sorangicin A Show In Vitro Activity against Mycobacterium abscessus Complex

The prevalence of lung disease caused by Mycobacterium abscessus is increasing among patients with cystic fibrosis. M. abscessus is a multidrug resistant opportunistic pathogen that is notoriously difficult to treat due to a lack of efficacious therapeutic regimens. Currently, there are no standard regimens, and treatment guidelines are based empirically on drug susceptibility testing. Thus, novel antibiotics are required. Natural products represent a vast pool of biologically active compounds that have a history of being a good source of antibiotics. Here, we screened a library of 517 natural products purified from fermentations of various bacteria, fungi, and plants against M. abscessus ATCC 19977. Lysobactin and sorangicin A were active against the M. abscessus complex and drug resistant clinical isolates. These natural products merit further consideration to be included in the M. abscessus drug pipeline. IMPORTANCE The many thousands of people living with cystic fibrosis are at a greater risk of developing a chronic lung infection caused by Mycobacterium abscessus. Since M. abscessus is clinically resistant to most anti-TB drugs available, treatment options are limited to macrolides. Despite macrolide-based therapies, cure rates for M. abscessus lung infections are 50%. Using an in-house library of curated natural products, we identified lysobactin and sorangicin A as novel scaffolds for the future development of antimicrobials for patients with M. abscessus infections.

Diversity, detection and exploitation: linking soil fungi and plant disease

Plant-associated fungi are incredibly diverse, comprising over a million species of mycorrhiza, endophytes, saprophytes and pathogens worldwide. This diverse fungal community is highly important for plant health. Many fungi are effective biocontrol agents that can kill or suppress fungal pathogens, with pathogen biocontrol found for both individual microorganisms and plant-associated fungal consortia. Meanwhile, increased plant community diversity aboveground corresponds to an increase in below-ground fungal community diversity, which contributes in turn to improved rhizosphere soil health and pathogen suppression. In this review, we discuss the role of fungal diversity in soil health and plant disease suppression and the various mechanisms by which mycorrhizal and endophytic fungi combat plant pathogenic fungi. We also discuss the array of diagnostic tools, both well-established and newly developed, which are revolutionising fungal pathogen detection and rhizosphere community analysis.

Pestalotiopsis Diversity: Species, Dispositions, Secondary Metabolites, and Bioactivities

Pestalotiopsis species have gained attention thanks to their structurally complex and biologically active secondary metabolites. In past decades, several new secondary metabolites were isolated and identified. Their bioactivities were tested, including anticancer, antifungal, antibacterial, and nematicidal activity. Since the previous review published in 2014, new secondary metabolites were isolated and identified from Pestalotiopsis species and unidentified strains. This review gathered published articles from 2014 to 2021 and focused on 239 new secondary metabolites and their bioactivities. To date, 384 Pestalotiopsis species have been discovered in diverse ecological habitats, with the majority of them unstudied. Some may contain secondary metabolites with unique bioactivities that might benefit pharmacology.

Note on the genus Nemania (Xylariaceae) - first records and a new species of the genus from Iran

In a survey of xylarialean fungi in northern Iran, some specimens attributable to the genus Nemania were collected, cultured and sequenced. Morphological evidence and phylogenetic analyses of a combined ITS, LSU, RPB2 and TUB2 gene dataset confirmed the presence of Nemaniadiffusa and N.serpens in Iran for the first time. Furthermore, the new species N.hyrcana, which shows similarities to N.subaenea and its putative synonym N.plumbea, but significantly differs from the latter in its DNA sequences, was encountered. All species are illustrated, described and discussed. In the phylogenetic analyses, for the first time, the overlooked ex-type ITS sequences of the neotype of the generic type, N.serpens and that of the holotype of N.prava, were added to a multi-gene matrix of Nemania. This revealed that the two accessions of N.serpens (HAST 235 and CBS 679.86), for which multigene data are available in GenBank, are misidentified, while the Iranian accession of N.serpens has an almost identical ITS sequence to the neotype, confirming its morphological species identification. The two previously accepted species of Euepixylon, E.udum and E.sphaeriostomum, are embedded within Nemania and are revealed as close relatives of N.serpens, supporting the inclusion of Euepixylon in Nemania.

A re-assessment of Taxomyces andreanae, the alleged taxol-producing fungus, using comparative genomics

The monotypic "bulbilliferous hyphomycete" genus Taxomyces was erected in 1993 for a fungal endophyte isolated from the Yew tree Taxus brevifolia and named Taxomyces andreanae. This fungus was reported to produce the plant-derived anti-cancer drug taxol. The original description of the fungus was not conclusive as to its taxonomic position because no sporulation or other salient morphological features were reported. Consequently, the taxonomic affinities of this fungus have remained obscure. However, a full genome sequence of this strain was generated by a German research group in 2013, in an unsuccessful attempt to detect the biosynthesis genes encoding for taxol. This prompted us to search for phylogenetic marker genes and compare those with the data that recently have become available from state-of-the-art polyphasic taxonomic studies. Surprisingly, the strain turned out to belong to the phlebioid clade of wood-destroying Basidiomycota as inferred from a comparison of its partial ITS, the 28S rDNA (LSU), the RNA polymerase II largest subunit (rpb1), the RNA polymerase II second largest subunit (rpb2), and the translation elongation factor 1-α (tef1) sequences. A multi gene genealogy based on these loci revealed that the closest relative is Ceriporiopsis (syn. Mycoacia) gilvescens. Even though such wood-destroying Basidiomycota are regularly encountered among the endophytic isolates after surface-disinfection of plant organs, the vast majority of the reported endophytic fungi belong to the Ascomycota. Nevertheless, the data available now allow for synonymizing Taxomyces with Ceriporiopsis, and the necessary new combination is made.

Studies on the secondary metabolism of Rosellinia and Dematophora strains (Xylariaceae) from Iran

The xylariaceous genus Dematophora has recently been resurrected and segregated from Rosellinia based on a molecular phylogeny and morphological characters. This was an important taxonomic change because Dematophora in the current sense contains several important pathogens, while Rosellinia is limited to mainly saprotrophic species that have an endophytic stage in their life cycle and may even have beneficial effects on the host plants. During our ongoing work on the functional biodiversity of the Xylariales, we have encountered new strains of rosellinoid Xylariaceae from Iran and have studied their mycelial cultures for secondary metabolites in an attempt to establish further chemotaxonomic affinities. In the process, we isolated and identified 13 compounds, of which rosellisteroid (1), the cichorine derivative 2, and the alkaloid 3 are new. Out of these, nine were tested for their antimicrobial affinities with cytochalasin E (6) exhibiting weak activity against Schizosaccharomyces pombe. The cytotoxicity of three cytochalasin derivatives was examined and their effects on the F-actin cytoskeletal organization studied by fluorescence microscopy using fluorescent phalloidin. Cytochalasin E (6) and Δ6,12-cytochalasin E (7) showed strong and irreversible action on actin, while cytochalasin K (8) exhibited weaker, reversible effects.

Metabolic Diversity of Xylariaceous Fungi Associated with Leaf Litter Decomposition

Fungi in the family Xylariaceae are primary agents of leaf litter decomposition. However, the diversity of carbon source utilization by xylariaceous fungi and the relative effects on this from environmental and phylogenetic factors are largely unknown. This study assessed the metabolic diversity and redundancy of xylariaceous fungi, associated with leaf litter decomposition, by measuring their in vitro capacity to utilize multiple carbon sources. The work identified the relative influences of geographic and climatic sources, as well as the taxonomic and phylogenetic relatedness, of the fungi. Using Biolog EcoPlate^TM, 43 isolates belonging to Nemania, Xylaria, Nodulisporium, Astrocystis, and Hypoxylon, isolated from Castanopsis sieboldii leaf litter at eight sites in Japan, were found to have the capacity to utilize a variety of carbohydrates, amino acids/amines, carboxylic acids, and polymers. The genera of xylariaceous fungi and their origins significantly affected their metabolic diversity and utilization of carbon sources. Variation partitioning demonstrated that dissimilarities in carbon utilization among fungal isolates were mostly attributable to site differences, especially climatic factors: mean annual temperature and precipitation, and maximum snow depth. Moreover, xylariaceous isolates that originated from adjacent sites tended to have similar patterns of carbon source utilization, suggesting metabolic acclimation to local environmental conditions.

Clinical-Epidemiology Aspect of Inpatients With Moderate or Severe COVID-19 in a Brazilian Macroregion: Disease and Countermeasures

COVID-19, also known as coronavirus disease 2019, is an infectious viral disease caused by SARS-CoV-2, a novel coronavirus. Since its emergence, its epidemiology has been explored; however, for some regions of the world, COVID-19’s behavior, incidence, and impact remain unclear. In continental nations like Brazil, this lack of knowledge results in nonuniform control, prevention, and treatment measures, which can be controversial in some locations. This study aimed to describe the epidemiological profile of patients with COVID-19 in the macroregion of Triângulo Sul in the state of Minas Gerais (MG), Brazil. Between March 25 and October 21, 2020, data were collected and statistically analyzed from 395 hospitalized patients in the city of Uberaba, MG, suspected to have moderate or severe forms of the disease. Of the 395 suspected cases, 82% were confirmed to be positive for COVID-19. The mean age of positive patients was 58.4 years, and 60.76% were male. Following these patients throughout their hospitalization, a mortality rate of 31.3% was observed. In the population positive for COVID-19, the risk of death increased by 4% for each year of the patient’s age. Likewise, the older the patient, the longer their hospitalization and the higher the risk of developing acute respiratory failure. Among the treatments tested in patients, heparin was associated with protection against mortality, and the absence of anticoagulant use was linked to a more than six times greater risk of death. Finally, comorbidities in patients with COVID-19 were positively correlated with increased hospitalization time. In summary, this study revealed that age, presence of comorbidities, length of hospitalization, and drug treatment considerably altered COVID-19’s lethality. To understand infection rates and the factors involved in COVID-19’s lethality, knowledge of the local epidemiology is necessary.

Cultivable Fungal Endophytes in Roots, Rhizomes and Leaves of Posidonia oceanica (L.) Delile along the Coast of Sicily, Italy

The presence of endophytic fungi in the roots, rhizomes, and leaves of Posidonia oceanica was evaluated in different localities of the Sicilian coast. Samples of roots, rhizomes, and leaves were submitted to isolation techniques, and the obtained fungal colonies were identified by morphological and molecular (rRNA sequencing) analysis. Fungal endophytes occurred mainly in roots and occasionally in rhizomes and leaves. Lulwoana sp. was the most frequent of the isolated taxa, suggesting a strong interaction with the host. In addition, eight other fungal taxa were isolated. In particular, fungi of the genus Ochroconis and family Xylariaceae were identified as endophytes in healthy plants at all sampling stations, whereas Penicillium glabrum was isolated at only one sampling station. Thus, several organs, especially roots of Posidonia oceanica, harbor endophytic fungi, potentially involved in supporting the living host as ascertained for terrestrial plants.

Fungi in the Antarctic Cryosphere: Using DNA Metabarcoding to Reveal Fungal Diversity in Glacial Ice from the Antarctic Peninsula Region

We assessed fungal diversity present in glacial from the Antarctic Peninsula using DNA metabarcoding through high-throughput sequencing (HTS). We detected a total of 353,879 fungal DNA reads, representing 94 genera and 184 taxa, in glacial ice fragments obtained from seven sites in the north-west Antarctic Peninsula and South Shetland Islands. The phylum Ascomycota dominated the sequence diversity, followed by Basidiomycota and Mortierellomycota. Penicillium sp., Cladosporium sp., Penicillium atrovenetum, Epicoccum nigrum, Pseudogymnoascus sp. 1, Pseudogymnoascus sp. 2, Phaeosphaeriaceae sp. and Xylaria grammica were the most dominant taxa, respectively. However, the majority of the fungal diversity comprised taxa of rare and intermediate relative abundance, predominately known mesophilic fungi. High indices of diversity and richness were calculated, along with moderate index of dominance, which varied among the different sampling sites. Only 26 (14%) of the total fungal taxa detected were present at all sampling sites. The identified diversity was dominated by saprophytic taxa, followed by known plant and animal pathogens and a low number of symbiotic fungi. Our data suggest that Antarctic glacial ice may represent a hotspot of previously unreported fungal diversity; however, further studies are required to integrate HTS and culture approaches to confirm viability of the taxa detected.

Trichoderma-derived pentapeptides from the infected nest mycobiome of the subterranean termite Coptotermes testaceus

Termites live in a dynamic environment where colony health is strongly influenced by surrounding microbes. However, little is known about the mycobiomes of lower termites and their nests, and how these change in response to disease. Here we compared the individual and nest mycobiomes of a healthy subterranean termite colony (Coptotermes testaceus) to one infected and ultimately eradicated by a fungal pathogen. We identified Trichoderma species in the materials of both nests, but they were also abundant in the infected termites. Methanolic extracts of Trichoderma sp. FHG000531, isolated from the infected nest, were screened for secondary metabolites by UHPLC‐HR MS/MS‐guided molecular networking. We identified many bioactive compounds with potential roles in the eradication of the infected colony, as well as a cluster of six unknown peptides. The novel peptide FE011 was isolated and characterized by NMR spectroscopy. The function of this novel peptide family as well as the role of Trichoderma species in dying termite colonies therefore requires further investigation.

Multigene Phylogeny Reveals Endophytic Xylariales Novelties from Dendrobium Species from Southwestern China and Northern Thailand

Xylariales are common endophytes of Dendrobium. However, xylarialean species resolution remains difficult without sequence data and poor sporulation on artificial media and asexual descriptions for only several species and old type material. The surface-sterilized and morph-molecular methods were used for fungal isolation and identification. A total of forty-seven strains were identified as twenty-three species belonging to Apiosporaceae, Hypoxylaceae, Induratiaceae, and Xylariaceae. Five new species—Annulohypoxylon moniliformis, Apiospora dendrobii, Hypoxylon endophyticum, H. officinalis and Nemania dendrobii were discovered. Three tentative new species were speculated in Xylaria. Thirteen known fungal species from Hypoxylon, Nemania, Nigrospora, and Xylaria were also identified. Another two strains were only identified at the genus and family level (Induratia sp., Hypoxylaceae sp.). This study recorded 12 new hosts for xylarialean endophytes. This is the first report of Xylariales species as endophytes from Dendrobium aurantiacum var. denneanum, D. cariniferum, D. harveyanum, D. hercoglossum, D. moniliforme, and D. moschatum. Dendrobium is associated with abundant xylarialean taxa, especially species of Hypoxylon and Xylaria. We recommend the use of oat agar with low concentrations to induce sporulation of Xylaria strains.

Photographic record of Armillaria mellea a bioluminescent fungi from Lonavala in Western Ghats, India

Armillaria mellea is a bioluminescent fungus from the Basidiomycota division. The previous known record of the fungus is from Bhimashankar Wildlife Sanctuary. This paper provides data and photographic evidence of Armillaria mellea in Lonavala. 

Ecological generalism drives hyperdiversity of secondary metabolite gene clusters in xylarialean endophytes

Although secondary metabolites are typically associated with competitive or pathogenic interactions, the high bioactivity of endophytic fungi in the Xylariales, coupled with their abundance and broad host ranges spanning all lineages of land plants and lichens, suggests that enhanced secondary metabolism might facilitate symbioses with phylogenetically diverse hosts. Here, we examined secondary metabolite gene clusters (SMGCs) across 96 Xylariales genomes in two clades (Xylariaceae s.l. and Hypoxylaceae), including 88 newly sequenced genomes of endophytes and closely related saprotrophs and pathogens. We paired genomic data with extensive metadata on endophyte hosts and substrates, enabling us to examine genomic factors related to the breadth of symbiotic interactions and ecological roles. All genomes contain hyperabundant SMGCs; however, Xylariaceae have increased numbers of gene duplications, horizontal gene transfers (HGTs) and SMGCs. Enhanced metabolic diversity of endophytes is associated with a greater diversity of hosts and increased capacity for lignocellulose decomposition. Our results suggest that, as host and substrate generalists, Xylariaceae endophytes experience greater selection to diversify SMGCs compared with more ecologically specialised Hypoxylaceae species. Overall, our results provide new evidence that SMGCs may facilitate symbiosis with phylogenetically diverse hosts, highlighting the importance of microbial symbioses to drive fungal metabolic diversity.

Fungal Endophytes and Their Role in Agricultural Plant Protection against Pests and Pathogens

Virtually all examined plant species harbour fungal endophytes which asymptomatically infect or colonize living plant tissues, including leaves, branches, stems and roots. Endophyte-host interactions are complex and span the mutualist-pathogen continuum. Notably, mutualist endophytes can confer increased fitness to their host plants compared with uncolonized plants, which has attracted interest in their potential application in integrated plant health management strategies. In this review, we report on the many benefits that fungal endophytes provide to agricultural plants against common non-insect pests such as fungi, bacteria, nematodes, viruses, and mites. We report endophytic modes of action against the aforementioned pests and describe why this broad group of fungi is vitally important to current and future agricultural practices. We also list an extensive number of plant-friendly endophytes and detail where they are most commonly found or applied in different studies. This review acts as a general resource for understanding endophytes as they relate to potential large-scale agricultural applications.

Fungal diversity notes 1512-1610: taxonomic and phylogenetic contributions on genera and species of fungal taxa

This article is the 14th in the Fungal Diversity Notes series, wherein we report 98 taxa distributed in two phyla, seven classes, 26 orders and 50 families which are described and illustrated. Taxa in this study were collected from Australia, Brazil, Burkina Faso, Chile, China, Cyprus, Egypt, France, French Guiana, India, Indonesia, Italy, Laos, Mexico, Russia, Sri Lanka, Thailand, and Vietnam. There are 59 new taxa, 39 new hosts and new geographical distributions with one new combination. The 59 new species comprise Angustimassarina kunmingense, Asterina lopi, Asterina brigadeirensis, Bartalinia bidenticola, Bartalinia caryotae, Buellia pruinocalcarea, Coltricia insularis, Colletotrichum flexuosum, Colletotrichum thasutense, Coniochaeta caraganae, Coniothyrium yuccicola, Dematipyriforma aquatic, Dematipyriforma globispora, Dematipyriforma nilotica, Distoseptispora bambusicola, Fulvifomes jawadhuvensis, Fulvifomes malaiyanurensis, Fulvifomes thiruvannamalaiensis, Fusarium purpurea, Gerronema atrovirens, Gerronema flavum, Gerronema keralense, Gerronema kuruvense, Grammothele taiwanensis, Hongkongmyces changchunensis, Hypoxylon inaequale, Kirschsteiniothelia acutisporum, Kirschsteiniothelia crustaceum, Kirschsteiniothelia extensum, Kirschsteiniothelia septemseptatum, Kirschsteiniothelia spatiosum, Lecanora immersocalcarea, Lepiota subthailandica, Lindgomyces guizhouensis, Marthe asmius pallidoaurantiacus, Marasmius tangerinus, Neovaginatispora mangiferae, Pararamichloridium aquisubtropicum, Pestalotiopsis piraubensis, Phacidium chinaum, Phaeoisaria goiasensis, Phaeoseptum thailandicum, Pleurothecium aquisubtropicum, Pseudocercospora vernoniae, Pyrenophora verruculosa, Rhachomyces cruralis, Rhachomyces hyperommae, Rhachomyces magrinii, Rhachomyces platyprosophi, Rhizomarasmius cunninghamietorum, Skeletocutis cangshanensis, Skeletocutis subchrysella, Sporisorium anadelphiae-leptocomae, Tetraploa dashaoensis, Tomentella exiguelata, Tomentella fuscoaraneosa, Tricholomopsis lechatii, Vaginatispora flavispora and Wetmoreana blastidiocalcarea. The new combination is Torula sundara. The 39 new records on hosts and geographical distribution comprise Apiospora guiyangensis, Aplosporella artocarpi, Ascochyta medicaginicola, Astrocystis bambusicola, Athelia rolfsii, Bambusicola bambusae, Bipolaris luttrellii, Botryosphaeria dothidea, Chlorophyllum squamulosum, Colletotrichum aeschynomenes, Colletotrichum pandanicola, Coprinopsis cinerea, Corylicola italica, Curvularia alcornii, Curvularia senegalensis, Diaporthe foeniculina, Diaporthe longicolla, Diaporthe phaseolorum, Diatrypella quercina, Fusarium brachygibbosum, Helicoma aquaticum, Lepiota metulispora, Lepiota pongduadensis, Lepiota subvenenata, Melanconiella meridionalis, Monotosporella erecta, Nodulosphaeria digitalis, Palmiascoma gregariascomum, Periconia byssoides, Periconia cortaderiae, Pleopunctum ellipsoideum, Psilocybe keralensis, Scedosporium apiospermum, Scedosporium dehoogii, Scedosporium marina, Spegazzinia deightonii, Torula fici, Wiesneriomyces laurinus and Xylaria venosula. All these taxa are supported by morphological and multigene phylogenetic analyses. This article allows the researchers to publish fungal collections which are important for future studies. An updated, accurate and timely report of fungus-host and fungus-geography is important. We also provide an updated list of fungal taxa published in the previous fungal diversity notes. In this list, erroneous taxa and synonyms are marked and corrected accordingly.

Anti-inflammatory and anti-proliferative activities of chemical constituents from fungus Biscogniauxia whalleyi SWUF13-085

The fungus Biscogniauxia whalleyi SWUF13-085 from the Graphostomataceae family was studied for potential anti-inflammatory and anticancer agents. A diverse array of natural products was identified. Six of which were undescribed compounds, including xylariterpenoids L-N, (1R,2S,6R,7S)-1,2-dihydroxy-α-bisabolol, 6-[(1R)-1-hydroxy-1-methyl-2-propenyl]-4-methoxy-3-methyl-2H-pyran-2-one and (1R*,4S*,5S*,7S*,10R*)-guaia-11 (12)-en-7,10-diol. Several of the isolated compounds such as bergamotene, guaiane and phthalide derivatives showed activity in both the inhibition of nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage cells with IC₅₀ values in the range of 2.48-10.82 μg/mL and anti-proliferation against HeLa cells with IC₅₀ values in the range of 8.64-31.16 μg/mL. While compounds such as cerebrosides A and C only exhibited inhibitory effects on NO production with IC₅₀ values in the range of 4.45-10.28 μg/mL.

Morphology and Phylogeny Reveal Vamsapriyaceae fam. nov. (Xylariales, Sordariomycetes) with Two Novel Vamsapriya Species

Phylogenetic analyses of combined LSU, rpb2, tub2 and ITS sequence data of representative Xylariales taxa indicated that Diabolocovidia, Didymobotryum and Vamsapriya cluster together and form a distinct clade in Xylariales. Morphological comparison also shows their distinctiveness from other families of Xylariales. Therefore, we introduce it as a novel family, Vamsapriyaceae. Based on morphological characteristics, Podosporium and Tretophragmia, which were previously classified in Ascomycota genera incertae sedis, are now included in the Vamsapriyaceae. In addition, three Vamsapriya species, V. chiangmaiensis sp. nov, V. uniseptata sp. nov, and V. indica are described and illustrated in this paper.

Evaluation of the Antibacterial Activity of Crude Extracts Obtained From Cultivation of Native Endophytic Fungi Belonging to a Tropical Montane Rainforest in Colombia

Bioactive secondary metabolite production from endophytic fungi has gained a recurring research focus in recent decades as these microorganisms represent an unexplored biological niche for their diverse biotechnological potential. Despite this focus, studies involving tropical endophytes remain scarce, particularly those isolated from medicinal plants of these ecosystems. In addition, the state of the art of the pharmaceutical industry has experienced stagnation in the past 30years, which has pushed pathogenic infections to get one step ahead, resulting in the development of resistance to existing treatments. Here, five fungal endophytes were isolated from the medicinal plant Otoba gracilipes (Myristicaceae), which corresponded to the genera Xylaria and Diaporthe, and screened to demonstrate the promissory potential of these microorganisms for producing bioactive secondary metabolites with broad-spectrum antibacterial activities. Thus, the evaluation of crude organic extracts obtained from the mycelia and exhaust medium allowed the elucidation of Xylaria sp. and Diaporthe endophytica potential toward providing crude extracellular extracts with promising bioactivities against reference strains of Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 25923), according to the determined half-maximum inhibitory concentration (IC₅₀) with values down to 3.91 and 10.50mg/ml against each pathogen, respectively. Follow-up studies provided insights into the polarity nature of bioactive compounds in the crude extracts through bioactivity guided fractionation using a polymeric resin absorbent alternative extraction procedure. In addition, evaluation of the co-culturing methods demonstrated how this strategy can enhance endophytes biosynthetic capacity and improve their antibacterial potential with a 10-fold decrease in the IC₅₀ values against both pathogens compared to the obtained values in the preliminary evaluations of Xylaria sp. and D. endophytica crude extracts. These results support the potential of Colombian native biodiversity to provide new approaches concerning the global emergence of antibiotics resistance and future production of undiscovered compounds different from the currently used antibiotics classes and simultaneously call for the value of preserving native habitats due to their promising ecosystemic applications in the biotechnological and pharmaceutical industries.

Antioxidant Activity and Cytotoxicity against Cancer Cell Lines of the Extracts from Novel Xylaria Species Associated with Termite Nests and LC-MS Analysis

Xylaria species associated with termite nests or soil have been considered rare species in nature and the few which have been reported upon have been found to act as a rich source of bioactive metabolites. This study evaluated 10 ethyl acetate extracts of five new Xylaria species associated with termite nests or soil for their antioxidant activity, and cytotoxicity against different cancer and normal cell lines. DPPH and ABTS radical scavenging activities of the extracts demonstrated strong capacity with low IC₅₀ values. The highest observed activities belonged to X. vinacea SWUF18-2.3 having IC₅₀ values of 0.194 ± 0.031 mg/mL for DPPH assay and 0.020 ± 0.004 mg/mL for ABTS assay. Total phenolic content ranged from 0.826 ± 0.123 to 3.629 ± 0.381 g GAE/g crude extract which correlated with antioxidant activities. The high total phenolic content could contribute to the high antioxidant activities. Cytotoxicity was recorded against A549, HepG2, HeLa and PNT2 and resulted in broad spectrum to specific activity depending on the cell lines. The highest activities were observed with X. subintraflava SWUF16-11.1 which resulted in 11.15 ± 0.32 to 13.17 ± 2.37% cell viability at a concentration of 100 µg/mL. Moreover, LC-MS fingerprints indicated over 61 peaks from all isolates. There were 18 identified and 43 unidentified compounds compared to mass databases. The identified compounds were from various groups of diterpenoids, diterpenes, cytochalasin, flavones, flavonoids, polyphenols, steroids and derivatives, triterpenoids and tropones. These results indicate that Xylaria spp. has abundant secondary metabolites that could be further explored for their therapeutic properties.

Identification of Antagonistic Compounds between the Palm Tree Xylariale Endophytic Fungi and the Phytopathogen Fusarium oxysporum

To discover microorganisms that naturally possess chemical weapons against the phytopathogen Fusarium oxysporum, the biological and chemical diversity of plant leaf endophytes was investigated. Endophytes were isolated from the palm tree Astrocaryum sciophyllum collected in pristine forests of French Guiana. Several Xylariaceae inhibited the growth of F. oxysporum and were further explored. Antifungal specialized metabolites were isolated from the Xylariaceae BSNB-0294 strain in confrontation with the phytopathogen and led to the identification of undescribed compounds, i.e., two depsipeptides named xylariaceins, two metabolites containing a 3-imidazolinone moiety, and four new compounds including a nitro-phenylpropanamide and three phenylalanine analogues named xylariains A-D. In parallel, the chemical investigation of the phytopathogen during the coculture led to the identification of an unknown compound, which we named focicin. The production of focicin was exacerbated during the competition. Matrix-assisted laser desorption/ionization coupled to time-of-flight mass spectometry (MALDI-TOF MS) imaging of the competition between BSNB-0294 (endophytic strain) and F. oxysporum f.sp. ciceris (phytopathogen) highlighted time-dependent chemical interactions between the two microorganisms.

Culturable Fungal Community of Pterocladiella capillacea in Keelung, Taiwan: Effects of Surface Sterilization Method and Isolation Medium

Fungi associated with macroalgae are less known when compared with those on wood in the marine environment. In this study, we assessed the diversity of fungi associated with the red alga Pterocladiella capillacea at Chao-Jin Park, Keelung, Taiwan. Algal segments of healthy and dead thalli were washed/sterilized with different solutions (sterile artificial seawater, 70% ethanol, and 4% sodium hypochlorite), plated on three different media (glucose-yeast extract-peptone seawater agar (GYPS), potato dextrose seawater agar (PDAS), and artificial seawater agar (SA)), and isolated as pure cultures. Identification was mainly based on BLAST search analysis of the internal transcribed spacers of rDNA (ITS). The highest isolation frequency (no. of segment with fungi/total no. of segment × 100) was in dead thalli (61.23%), thalli washed with seawater (88.38%), and thalli plated on GYPS (62.10%). A total of 3187 isolates were cultured, representing 129 taxa (in 67 genera); the higher species richness was isolated from healthy thalli (119 species), thalli washed with seawater (111 species), and on GYPS (112 species). Ascomycota (Eurotiales, Hypocreales, Capnodiales, Pleosporales, Xylariales) dominated the fungal community in P. capillacea with many basidiomycetous yeasts and few Mucoromycota. Aspergillus, Cladosporium, Penicillium (Ascomycota), and Rhodosporidium (Basidiomycota) were the dominant genera associated with the alga. The surface washing/sterilization schemes of algal thalli affected fungal diversity, but the isolation media used did not. While these genera are known producers of antimicrobial secondary metabolites, they might form a mutualistic relationship with P. capillacea by exchanging nutrients from photosynthesis for protection from microbial diseases.

Secondary metabolite biosynthetic diversity in the fungal family Hypoxylaceae and Xylaria hypoxylon

To date little is known about the genetic background that drives the production and diversification of secondary metabolites in the Hypoxylaceae. With the recent availability of high-quality genome sequences for 13 representative species and one relative (Xylaria hypoxylon) we attempted to survey the diversity of biosynthetic pathways in these organisms to investigate their true potential as secondary metabolite producers. Manual search strategies based on the accumulated knowledge on biosynthesis in fungi enabled us to identify 783 biosynthetic pathways across 14 studied species, the majority of which were arranged in biosynthetic gene clusters (BGC). The similarity of BGCs was analysed with the BiG-SCAPE engine which organised the BGCs into 375 gene cluster families (GCF). Only ten GCFs were conserved across all of these fungi indicating that speciation is accompanied by changes in secondary metabolism. From the known compounds produced by the family members some can be directly correlated with identified BGCs which is highlighted herein by the azaphilone, dihydroxynaphthalene, tropolone, cytochalasan, terrequinone, terphenyl and brasilane pathways giving insights into the evolution and diversification of those compound classes. Vice versa, products of various BGCs can be predicted through homology analysis with known pathways from other fungi as shown for the identified ergot alkaloid, trigazaphilone, curvupallide, viridicatumtoxin and swainsonine BGCs. However, the majority of BGCs had no obvious links to known products from the Hypoxylaceae or other well-studied biosynthetic pathways from fungi. These findings highlight that the number of known compounds strongly underrepresents the biosynthetic potential in these fungi and that a tremendous number of unidentified secondary metabolites is still hidden. Moreover, with increasing numbers of genomes for further Hypoxylaceae species becoming available, the likelihood of revealing new biosynthetic pathways that encode new, potentially useful compounds will significantly improve. Reaching a better understanding of the biology of these producers, and further development of genetic methods for their manipulation, will be crucial to access their treasures.

Pithohirolide, an antimicrobial tetradepsipeptide from a fungus Pithomyces chartarum

Pithohirolide (1), a new depsipeptide, was isolated from an ascomycetous fungus Pithomyces chartarum TAMA 581. The planar structure of 1 was elucidated on the basis of NMR and MS analyses and the absolute configuration was determined by the advanced Marfey's analysis, chiral-phase HPLC analysis, and synthesis of degradation product. Compound 1 possesses a cyclic structure comprising (S)-2-hydroxy-3-phenylpropanoic acid, (S)-3-hydroxy-3-phenylpropanoic acid, (S)-2-hydroxyisovaleric acid, and N-methyl-L-alanine, connected via three ester and one amide linkages. Compound 1 exhibited antimicrobial activity against Staphylococcus aureus and Saccharomyces cerevisiae at MIC 3.1 μg ml^-1.